Retractable buffer stop

ABSTRACT

A retractable buffer stop of the type to be installed in a pit between the rails is disclosed. The buffer stop generally comprises an actuating arm, a pair of supporting arms and a hydraulic power cylinder which serves to raise or lower the actuating arm. They are so interconnected as to form a straightline mechanism in order to permit an impact head pivoted to the upper end of the actuating arm to make a straight linear motion in the horizontal direction when the car strikes against the buffer stop. The impact head is also coupled through a parallel linkage to the pivot pin at the lower end of the actuating arm so that the impact receiving surface of the impact head may be always maintained vertically. A hydraulic shock absorber is also provided to absorb the impact from the car. Since the impact head may make a straight linear motion in the horizontal direction and its impact receiving surface may be always maintained vertically the impact forces from the car may be uniformly distributed over the retractable buffer stop.

United States Patent [191 Kikuchi et al.

[4 1 Mar. 26, 1974 RETRACTABLE BUFFER STOP [75] Inventors: Takashi Kikuchi, O-Miya;

Toshitsune Motoki, Tokyo; Hideo Kobayashi, Yokohama; Toshiaki Kamei, Tokyo, all of Japan [73] Assignees: Japanese National Railways, Tokyo;

Kayabokogyokabushikikaisha, Minato-ku, Tokyo, both of, Japan [22] Filed: Jan. 24, 1973 [21] Appl. No.: 326,390

[30] Foreign Application Priority Data Jan. 25, 1972 Japan 47-9377 [52] US. Cl. 104/256, 104/252 [51] Int. Cl .i B6lk 7/18 [58] Field of Search 104/256, 249, 254, 255

[56] References Cited FOREIGN PATENTS OR APPLICATIONS 699937 ll/l953 Great Britain 104/254 Primary ExaminerGerald M. Forlenza Assistant Examiner-Kenneth Noland Attorney, Agent, or FirmSaul Jecies [57] ABSTRACT A retractable buffer stop of the type to be installed in a pit between the rails is disclosed. The buffer stop generally comprises an actuating arm, a pair of supporting arms and a hydraulic power cylinder which serves to raise or lower the actuating arm. They are so interconnected as to form a straight-line mechanism in order to permit an impact head pivoted to the upper end of the actuating arm to make a straight linear motion in the horizontal direction when the car strikes against the buffer stop. The impact head is also coupled through a parallel linkage to the pivot pin at the lower end of the actuating arm so that the impact receiving surface of the impact head may be always maintained vertically. A hydraulic shock absorber is also provided to absorb the impact from the car. Since the impact head may make a straight linear motion in the horizontal direction and its impact receiving surface may be always maintained vertically the impact forces from the car may be uniformly distributed over the retractable buffer stop.

6 Claims, 4 Drawing Figures PATENTEU 826 I874 SHEEI 3 BF 3 RETRACTABLE BUFFER STOP BACKGROUND OF THE INVENTION The present invention relates to generally a retractable buffer stop for retarding and stopping a freight car or the like or permitting it to pass over it freely, and more particularly retractable buffer stops adapted to be installed in a freight car classification yard in order to sort and stop the frieght cars released from a switch engine or hump.

In the mines and railroad yards the cars must be stopped at a predetermined position. Since the cars are moving at a certain speed the considerable impact forces are exerted to the buffer stops or the like. Therefore the buffer stops must be robust in construction yet compact in size and reliable and dependable in operation.

The conventional buffer stops may be divided generally into two types. In one type an elastic buffer means which is directly or indirectly mounted on an impact receiving member of the buffer stop absorbs the impact forces from the moving car so as to stop it at a predetermined position. In other type an actuating arm against the upper end of which strikes the coupling or the like of a moving car is coupled to a hydraulic shock absorber and to a hydraulic power cylinder which serves to raise or lower the actuating arm so that the impact forces exerted to the buffer stop may be absorbed by the hydraulic shock absorber when the moving car is stopped at a predetermined position. In the former type the elastic member must be made considerably large in size in order to sufficiently absorb the great impact forces exerted from the moving car so that the buffer stop becomes considerably large in size. Furthermore when the moving car strikes against the impact receiving member at a high speed the latter will be damaged by the great reaction forces caused by the elastic member. In the worst case, the whole system will be damaged seriously. In the latter type because of the use of the hydraulic shock absorber together with the linkage, the buffer stop may be made compact in size, but it has a defect that the point of the actuating arm at which the coupling of a car engages with the actuating arm is gradually shifted as the actuating arm swings about its pivot pin. Therefore the excessive impact forces are exerted to the actuating arm so that its pivot pin is susceptible to damage within a relatively short operational time. In the worst case the runaway happens.

SUMMARY OF THE INVENTION One of the objects of the present invention is therefore to provide a linkage type retractable buffer stop in which the upper end of an actuating member against which the coupling of a moving car strikes may make a straight linear horizontal motion so that no excessive impact forces may be exerted to the actuating arm when the car is retarded and stopped.

Briefly stated, according to the present invention an impact head against which strikes the coupling of a moving car is pivotably fixed to the upper end of an actuating arm having at a suitable point between its ends pivotably fixed to a pair of supporting arms which in turn are pivotably fixed to a stationary member such as a side wall in a pit between a pair of rails, the lower end of the actuating arm being pivotably fixed to the piston of a hydraulic actuating cylinder which in turn is pivotably fixed to a stationary member and serves to raise or lower the actuating arm. Furthermore a hydraulic shock absorber is interposed between the actuating arm and a stationary member or side wall in the pit so that the impact forces exerted from the moving car to the actuating arm may be absorbed. By virtue of the cooperation of the hydraulic shock absorber and the hydraulic actuating cylinder the upper end of the actuating arm and hence the impact head may make a straight linear horizontal motion. The impact head pivoted to the upper end of the actuating arm is coupled through a parallel linkage to the pivot pin with which the lower end of the actuating arm is pivotably fixed to the piston rod of the hydraulic actuating cylinder so that the impact receiving surface of the impact head may be always maintained vertically regardless of the swinging motion of the actuating arm.

When the coupling of a moving car strikes against the impact head at the upper end of the actuating arm of the retractable buffer stop in accordance with the present invention, the impact head may make a straight linear horizontal motion while the impact receiving surface thereof may be maintained vertically so that the impact forces may be uniformly distributed over the impact receiving surface of the impact head. Therefore no excessive impact force will be exerted to any component parts of the retractable buffer stop in accordance with the present invention and the cars may be retarded and stopped in a very efficient manner. Thus the present invention may provide a retractable retarder which is compact in size and very reliable and dependable in operation and has a long service life.

The above and other objects, features and advantages of the present invention will become more apparent from the following description of one preferred embodiment thereof taken in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a front view of a retractable buffer stop in accordance with the present invention illustrating in the operative position for stopping or retarding a freight car;

FIG. 2 is a side view thereof;

FIG. 3 is a top view thereof; and

FIG. 4 is a front view thereof illustrating the retracted position.

DESCRIPTION OF THE PREFERRED EMBODIMENT One preferred embodiment of a retractable buffer stop in accordance with the present invention will be described as being installed in a freight car classification yard, but it is to be understood that the retractable buffer stops in accordance with the present invention may be utilized for various purposes in the railroad system.

A retractable buffer stop generally indicated by 10 is installed within a pit 16 between a pair of rails 14 on which rides a freight car 12.

The buffer stop 10 generally comprises an actuating arm 18 located in the deep pit portion 16a, a hydraulic shock absorber 20 installed in the shallow pit portion 16b and operatively coupled to the actuating arm 18 as will be described in more detail hereinafter, a pair of supporting arms 22, and an actuating cylinder 24 located in the deep pit portion 160.

The hydraulic shock absorber is of the conventional horizontal type having a piston rod 26 which is normally extended. The base of the hydraulic shock absorber 20 is securely fixed to the side wall 28 in the shallow pit portion 16b. To the free end of the piston rod 26 is pivoted the base end of a connecting rod 32 with a pin or shaft 30 for vertically angular movement. The other end of the connecting rod 32 is pivoted with a pin or shaft 34 to the actuating arm 18 for vertically angular movement.

Each of the supporting arms 22 is pivoted with a shaft or pin to a bracket 38 installed in a recess 36 formed in each side wall of the pit 16 as best shown in FIG. 2. The supporting arms 22 are also pivoted to the actuating arm 18 with the shaft or pin 34. Therefore the actuating arm 18 is partly supported by the supporting arms 22 and the connecting rod 32 extending from the hydraulic shock absorber 20.

The base of the actuating cylinder 24 is pivoted to a bracket 44 which in turn is securely fixed to the side wall42 of the deep pit portion 16a which defines the boundary between the deep and shallow pit portions 160 and 16b. The free end of a piston rod extending from a piston 48 mounted within the actuating cylinder 24 is pivoted with a shaft or pin 52 to the lower end of the actuating arm 18.

According to the present invention, when the hydraulic power cylinder 24 is locked in its retracted position as shown in FIG. 1, the actuating arm 18, the pair of supporting arms 22, and the hydraulic power cylinder 24 form a straight-line mechanism so that the upper end of the actuating arm 18 may make a straight linear motion in the horizontal direction as indicated by the chain lines in FIG. 1 when the coupling 86 or the like of the freight car 12 strikes against the actuating arm 18. Therefore the engagement of the coupling 86 of the freight car I2 with the actuating arm 18 will remain unchanged in position when the car 12 is retarded and stopped.

The working oil under pressure is forced into the actuating cylinder 24 through ports 54 and 56, the former being normally communicated with a source of working oil under pressure. Therefore the working oil under pressure is normally supplied into the left chamber 58 in the actuating cylinder 24 so that the piston rod 50 is locked in the retracted position. The right port 56 is selectively communicated with the working oil or high pressure source or a sump through a switching valve (not shown). The port 56 is normally communicated with the sump so that the piston rod 50 is locked in the retracted position so that the actuating arm 18 may be held in the raised position as shown in FIG. 1. However when the port 56 is communicated with the high pressure source so that the working oil under pressure is forced into the right chamber 60 in the cylinder 24 whereas the port 54 is communicated with the sump, the piston rod 50 is extended out of the cylinder 24 so that the actuating arm 18 is caused to rotate about the shaft 34 in the clockwise direction. As a result the actuating arm 18 is lowered into the deep pit portion 16a as shown in FIG. 4.

To the upper end of the actuating arm 18 is pivoted with a pin 62 an impact head 64 for vertically angular movement, and it comprises, as best shown in FIG. 3, a box-shaped member having a hole 68 opened at the forward end thereof, a head member 72 which is slidably disposed within the box-shaped member 70,.

and an initial load absorbing member 74 interposed between the box-shaped member 70 and the head member 72. In the instant embodiment the shock absorber 74 is shown as being a spring, but it is to be understood that any other suitable shock absorbing material such as rubber or the like may be employed.

On each side of the actuating arm 18 is disposed a parallel linkage comprising crank rods 74 and 76, a connecting rod 84 having a telescopic tube having a spring loaded therein and a turnbuckle 82 and the actuating arm 18. One ends of the crank rods 74 and 76 are fixed to the pins 62 and 52 respectively whereas the other ends are fixed to the upper and lower ends of the connecting rod 84, respectively. Therefore the impact receiving surface of the impact head 64 may be always maintained vertically regardless of the swinging motion of the actuating arm 18, and the slight inclination of the impact receiving surface of the impact head 64 relative to the vertical line caused by the swinging motion of the actuating cylinder 24 about the pivot pin 46 may be compensated by the telescopic tube 80 of the connecting rod 84. Therefore the impact receiving surface of the impact head 64 may be always maintained vertically.

Next the mode of operation of the retractable buffer stop with the construction described above will be explained hereinafter.

1. Car Retarding Operation The port 56 of the actuating cylinder 24 is communicated with the sump whereas the port 54 is communicated with the high pressure source so that the piston rod 50 is retracted. Therefore the lower end of the actuating arm 18 which is connected to the piston rod 50 with the pivot pin 52 is moved toward the actuating cylinder 24 whereas the hydraulic shock absorber 20 pushes the actuating arm 18 to the left through the connecting rod 32. As a result the actuating arm 18 swings about the pivot pin 34 in the counterclockwise direction so that the actuating arm 18 is extended out of the pit 16 into the raised position in which the actuating arm 18 is slightly inclined forwardly as best shown in FIG. 1. Thereafter the port 56 of the actuating cylinder 24 is disconnected from the high pressure source so that the actuating cylinder 24 is locked in position. Now the buffer stop 10 is held in position for retarding and stopping the car 12.

When the car 12 is approaching the buffer stop 10, the coupling 86 of the car 12 engages with the impact head 64 and pushes it backwardly, that is, to the left in FIG. 1. Since the actuating cylinder 24 is locked as described before the actuating arm 18 makes a swinging motion which is the the resultant swinging motion of the first and second swinging motions described above but the impact head 64 at the upper end of the actuating arm 18 makes a straight linear horizontal motion. In this case the impact receiving surface of the impact head 64 may be maintained vertically regardless of the swinging motion of the actuating arm 18 in the manner described hereinbefore so that the reliable and dependable engagement of the coupling 86 of the freight car 12 with the impact head 64 may be ensured and the impact force may be uniformly exerted to the impact head 64.

As the actuating arm 18 swings in the manner described above due to the impact exerted thereto from the car 12, the impact and the kinetic energy of the car 12 are gradually absorbed by the hydraulic shock absorber 20 as the connecting rod 32 and hence the piston rod 26 travel to the right. Thus the car 12 may be retarded and stopped at a predetermined position.

2. Actuating Arm Retracting Operation The ports 54 and 56 of the actuating cylinder 24 are communicated to the high pressure source so that the piston rod 50 is gradually extended. As a result the actuating arm 18 swings about the pivot pin 34 in the clockwise direction so that the actuating arm 18 may be lowered in the retracted position within the pit 16 as shown in FIG. 4. When the actuating arm 18 is held in the retracted position within the pit 16 the car 12 may pass over the retracted buffer stop freely because the coupling 86 of the car 12 will not engage with the impact head 64 at the upper end of the actuating arm 18.

As described hereinbefore according to the present invention the impact head 64 at the upper end of the actuating arm 18 of the retractable buffer stop may make a straight linear horizontalmotion of the actuating arm 18 while the impact receiving surface of the impact head 64 may be always maintained vertically. Therefore no excessive forces are exerted not only to the coupling 86 of the car 12 but also to the component parts of the retractable buffer stop 10.

Furthermore since the actuating arm 18 of the retractable buffer stop 10 may be lowered and held in the retracted position it will not be necessary to provide a deep pit 16 for freely passing the car 12. Thus the retractable buffer stop in accordance with the present invention may be made compact in size and light in weight.

The present invention has been described in detail with particular reference to one preferred embodiment thereof but it will be understood that variations and modifications can be effected within the spirit and scope of the present invention as described hereinabove and as defined in the appended claims.

What is claimed is:

1. A retractable buffer stop comprising a. an actuating arm (with the upper end of which strikes a coupling or the like of a car),

b. a pair of supporting arms pivoted to a point between the upper and lower ends of said actuating arm for permitting the angular movement thereof,

c. a connecting member pivoted to the lower end of said actuating arm so that said actuating member may swing relative to a stationary member,

d. a hydraulic shock absorber interposed between said point of said actuating arm and a stationary member for providing the retarding or braking force when the car strikes the retractable buffer stop, and

e. said actuating arm, said pair of supporting arms and said connecting member being so interconnected with each other as to form a straight-line mechanism so that the upper end of said actuating arm may make a straight linear motion in the horizontal direction when the car strikes against said upper end of said actuating arm.

2. A retractable buffer stop as defined in claim 1 wherein said connecting member comprises a hydraulic cylinder so that said actuating arm may be selectively held in raised operative position or in the lowered, retracted inoperative position by the actuating of said hydraulic cylinder.

3. A retractable buffer stop as defined in claim 2 wherein said hydraulic shock absorber has its base securely fixed to said stationary member and has a connecting rod pivotably fixed to the free end of the piston of said hydraulic shock absorber so that said hydraulic shock absorber may be operatively coupled to said point of said actuating arm through said connecting rod.

4. A retractable buffer stop as defined in claim 3 wherein said actuating arm has an impact head pivotably fixed to the upper end thereof, and

the pivot pin with which said impact head is pivotably fixed to said upper end of said actuating arm is coupled through a parallel linkage to the pivot pin at the lower end of said actuating arm with which the latter is pivotably fixed to the piston rod of said hydraulic cylinder whereby the impact receiving surface of said impact head may be always maintained vertically regardless of the movement of said actuating arm.

5. A retractable buffer stop as defined in claim 4 wherein said parallel linkage comprises a crank rod having one end thereof fixed to said pivot pin of said impact head, a crank rod having one end thereof fixed to said pivot pin at the lower end of said actuating arm, a connecting rod pivoted to the other ends of said two crank rods, said connecting rod having a telescopic tube portion disposed at a suitable point between the ends thereof.

6. A retractable buffer stop as defined in claim 5 wherein said impact head comprises a box-shaped member pivotably fixed to said upper end of said actuating arm,

a head member slidably fitted into said box-shaped member, and an initial load absorbing means interposed between said head member and said boxshaped member. s a: 

1. A retractable buffer stop comprising a. an actuating arm (with the upper end of which strikes a coupling or the like of a car), b. a pair of supporting arms pivoted to a point between the upper and lower ends of said actuating arm for permitting the angular movement thereof, c. a connecting member pivoted to the lower end of said actuating arm so that said actuating member may swing relative to a stationary member, d. a hydraulic shock absorber interposed between said point of said actuating arm and a stationary member for providing the retarding or braking force when the car strikes the retractable buffer stop, and e. said actuating arm, said pair of supporting arms and said connecting member being so interconnected with each other as to form a straight-line mechanism so that the upper end of said actuating arm may make a straight linear motion in the horizontal direction when the car strikes against said upper end of said actuating arm.
 2. A retractable buffer stop as defined in claim 1 wherein said connecting member comprises a hydraulic cylinder so that said actuating arm may be selectively held in raised operative position or in the lowered, retracted inoperative position by the actuating of said hydraulic cylinder.
 3. A retractable buffer stop as defined in claim 2 wherein said hydraulic shock absorber has its base securely fixed to said stationary member and has a connecting rod pivotably fixed to the free end of the piston of said hydraulic shock absorber so that said hydraulic shock absorber may be operatively coupled to said point of said actuating arm through said connecting rod.
 4. A retractable buffer stop as defined in claim 3 wherein said actuating arm has an impact head pivotably fixed to the upper end thereof, and the pivot pin with which said impact head is pivotably fixed to said upper end of said actuating arm is coupled through a parallel linkage to the pivot pin at the lower end of said actuating arm with which the latter is pivotably fixed to the piston rod of said hydraulic cylinder whereby the impact receiving surface of said impact head may be always maintained vertically regardless of the movement of said actuating arm.
 5. A retractable buffer stop as defined in claim 4 wherein said parallel linkage comprises a crank rod having one end thereof fixed to said pivot pin of said impact head, a crank rod having one end thereof fixed to said pivot pin at the lower end of said actuating arm, a connecting rod pivoted to the other ends of said two crank rods, said connecting rod having a telescopic tube portion disposed at a suitable point between the ends thereof.
 6. A retractable buffer stop as defined in claim 5 wherein said impact head comprises a box-shaped member pivotably fixed to said upper end of said actuating arm, a head member slidably fitted into said box-shaped member, and an initial load absorbing means interposed between said head member and said box-shaped member. 